In the publication "Funk-Technik", 1983, Heft 12 pages 498-500, there are discussed video recorders which involve recording video and FM-audio signals in oblique tracks in a magnetic tape. In this regard, the penetration depth of the magnetization of the magnetic tape corresponding to the video signal is lower than the penetration depth of the magnetization of the magnetic tape corresponding to the audio signal. The audio signal is also recorded on a longitudinal track at the edge of the magnetic tape. This is to assure the compatibility of the magnetic tape with conventional video recorders which do not record or playback FM-audio signals when they are recorded in the oblique tracks. Rather such video recorders use the longitudinal track for audio recording and playback.
During the playback of a recorded magnetic tape cassette some video recorders automatically switch over through the use of a detector circuit between an audio playback from the oblique tracks which has a high audio quality and an audio playback from the longitudinal track which has a reduced audio quality. This circuit recognizes the presence or absence of an oblique track-FM-audio recording.
In DE-PS 34 21 197 and corresponding EP-A2 0 166 861 there is discussed the use of a video magnetic tape on which had been already recorded a FM-audio signal and the subsequently adding of a recording of a television signal without erasing the already recorded FM-audio signal. In this regard, the video signal is recorded with a lower penetration depth of magnetization in the oblique tracks of the magnetic tape. The associated audio signal is exclusively in a longitudinal track on the tape edge.
In addition in DE-PS 35 15 251 and DE-PS 32 23 151 video recorders are discussed which are provided with a device for electronic cutting of video signals in the oblique tracks of a magnetic tape. These devices are provided with rotating eraser heads which erase the video signals which are recorded in the oblique tracks at marked tape locations. These marked tape locations are marked by the user by means of a control unit, so that subsequently new video signals can be recorded in the erased oblique tracks by means of the rotating video heads. However in such devices recording of FM-audio signals is not provided.
While it is desireable to record the video and audio signals on magnetic tape, it is also desirable to avoid a situation which is the result of the video recorder during playback switching from the audio signal being read from the oblique tracks at one point and the longitudinal track at another point. Such switching results in undesired noise.
Accordingly there exists a need for a video recorder which allows the electronic cutting of video signals along with audio signals in the oblique track portion.
It is a further object to provide such a video recording device with such a feature through the use of a small amount of additional circuitry.
It is a yet further object to provide for such a feature which results in a low interference in the audio signal.
These objects are provided by the present invention through the use of a video recorder which allows for the recording of the video portion in the oblique tracks and the use of the audio signals in the longitudinal track to record FM-audio signals in the oblique tracks.
The advantages of the present invention are particularly apparent in the recording of video and FM-audio signals in what are commonly referred to as "HiFi-video recorders". In this regard, recording in the oblique tracks includes an FM-audio signal in addition to a video signal with a longitudinal track at the tape edge also being provided for the audio signal. For recording the present invention provides for audio signals in the longitudinal track on the tape edge to be recorded as FM-audio signals in the oblique tracks. As such during the playback of the audio signal it can be taken from the oblique tracks alone thus avoiding any switch over noises generated if the signal was taken from the oblique track-FM-recording and then the audio signal on longitudinal track playback and back again. This such switching back and forth is eliminated.